scholarly journals A new concept for UAV landing gear shock vibration control using pre-straining spring momentum exchange impact damper

2016 ◽  
Vol 24 (8) ◽  
pp. 1455-1468 ◽  
Author(s):  
Lovely Son ◽  
Mulyadi Bur ◽  
Meifal Rusli
Keyword(s):  
Landing Gear ◽  
Main Body ◽  
Force Transmission ◽  
Momentum Exchange ◽  
Lumped Mass ◽  
Maximum Acceleration ◽  
Impact Damper ◽  
Aerial Vehicle ◽  
Theoretical Application ◽  
The Impact

This study proposes a new method for reducing the shock vibration response of an Unmanned Aerial Vehicle (UAV) during the landing process by means of the momentum exchange principle (MEID). The performance of the impact damper is improved by adding a pre-straining spring to the damper system. This research discusses the theoretical application of the damper to the UAV landing gear system. The UAV dynamics is first modeled as a simple lumped mass translational vibration system. Then we analyze a more complex two-dimensional model of UAV dynamics. This model consists of the main wheel, nose wheel and main body. Three cases of UAV landing gear mechanisms: without damper, with passive MEID (PMEID) and with pre-straining spring MEID (PSMEID) are simulated. The damper performance is evaluated from the maximum acceleration and force transmission to the main body. The energy balance calculation is conducted to investigate the performance of PSMEID. The simulation results show that the proposed PSMEID method is the most effective method for reducing the maximum acceleration and force transmission of UAV during impact landing.

Investigation into the linear velocity response of cantilever beam embedded with impact damper

2019 ◽  
Vol 25 (7) ◽  
pp. 1365-1378 ◽  
Author(s):  
Yiqing Yang ◽  
Xi Wang
Keyword(s):  
Cantilever Beam ◽  
Continuous System ◽  
Linear Velocity ◽  
Superposition Method ◽  
Momentum Exchange ◽  
Impact Damper ◽  
Mode Superposition Method ◽  
Velocity Response ◽  
The Impact ◽  
Nonlinear Velocity

The impact damper causes momentum exchange between the primary structure and impact mass, and achieves vibration attenuation through repeated collisions. A cantilever beam embedded with the impact damper is modeled in the form of a continuous system, and the equations of motion are formulated based on the mode superposition method. The mechanism of the impact damper is investigated, and linear velocity response is achieved by a proper selection of a mass ratio of 8.4%, clearance within 0.30 mm, and excitation force ranged from 3.2 N to 5.5 N. The reverse collision has higher damping than co-directional collision, based on which a new criterion of response regimes is proposed for the design of the impact damper. The velocity responses of the damped cantilever beam under sinusoidal and impulse excitation are simulated and verified via the sinusoidal sweep experiments. The velocity amplitudes of the damped cantilever beam are linearly decreased when the clearance is increased within 0.30 mm. Finally, linear and nonlinear velocity responses of the damped cantilever beam are discussed. It is found that the nonlinear velocity response reaches larger damping, but that a strongly modulated response exists.

Impact damper for axial vibration of a continuous system

2015 ◽  
Vol 230 (13) ◽  
pp. 2145-2157
Author(s):  
SB Sanap ◽  
SY Bhave ◽  
PJ Awasare
Keyword(s):  
Vibration Amplitude ◽  
Damping Ratio ◽  
Continuous System ◽  
Axial Vibration ◽  
Lumped Mass ◽  
Impact Damper ◽  
Forcing Function ◽  
Repetitive Impact ◽  
Sinusoidal Functions ◽  
The Impact

Application of Impact damper for reduction of vibration amplitude through momentum transfer is now well established. However, no literature is available for the effect of an impact damper on axial vibration of a rod as a continuous system. The equation for axial vibratory displacement of the rod, fixed at one end and a lumped mass at the other end, is derived by considering steady state vibrations having a period equal to that of the forcing function at the free end. Structural damping is assumed to be modal with a damping ratio of 0.005. Taking this periodicity into account, the repetitive impact force is resolved in the sinusoidal functions through Fourier series analysis. The forcing function thus will have components with the frequency of the external force and the multiple harmonic forces resulting from impacts. Since an infinite series is involved, the solution is obtained for a truncated series using MATLAB. It is observed that the damper is most effective when the Impact distribution parameter is equal to 0.5. The results of the numerical analysis are supported by experiments and are found to be in good agreement with the theoretical results. The reduction of vibration amplitude is observed to be dependent on the clearance (travel of impacting mass), mass ratio of the impacting mass to the main system, frequency of excitation, and the location of the stop in addition to the impact distribution.

A Novel Boat Shock Vibration Control using Momentum Exchange Principle with Pre-Straining Spring Mechanism

2020 ◽  
Vol 17 (2) ◽  
pp. 7858-7867
Author(s):  
L. Son ◽  
J. Malta ◽  
E. Satria ◽  
B. Yuliandra ◽  
H. Matsuhisa
Keyword(s):  
Wave Excitation ◽  
Momentum Exchange ◽  
Beam Structure ◽  
Mass System ◽  
Impact Damper ◽  
Vibration Attenuation ◽  
Spring Mechanism ◽  
The Impact ◽  
Impact Vibration ◽  
Better Than

This research proposes a new method for boat impact vibration attenuation using the exchange of momentum principle with a pre-straining spring mechanism. The boat dynamic is modeled using a hinged-supported beam structure. The wave excitation on the boat hull is expressed using one degree of freedom spring-mass system. The simulation study is performed to evaluate the impact damper performance in reducing the boat shock response. Two kinds of momentum exchange impact damper i.e., without and with pre-straining spring mechanism, are evaluated. The simulation results show that the impact damper with pre-straining spring mechanism (PSMEID) is better than the passive momentum exchange impact damper (PMEID) in reducing the boat shock vibration response

scholarly journals Performance of a New Fine Particle Impact Damper

2008 ◽  
Vol 2008 ◽  
pp. 1-6 ◽  
Author(s):  
Yanchen Du ◽  
Shulin Wang ◽  
Yan Zhu ◽  
Laiqiang Li ◽  
Guangqiang Han
Keyword(s):  
Fine Particle ◽  
Mechanical Vibration ◽  
Low Frequency ◽  
Particle Impact ◽  
Momentum Exchange ◽  
Impact Damper ◽  
Low Frequency Vibration ◽  
Cantilevered Beam ◽  
The Impact ◽  
First Time

The energy dissipation mechanisms of conventional impact damper (CID) are mainly momentum exchange and friction. During the impact process, a lot of vibration energy cannot be exhausted but reverberated among the vibration partners. Besides, the CID may produce the additional vibration to the system or even amplify the response in the low-frequency vibration. To overcome these shortcomings, this paper proposes a new fine particle impact damper (FPID) which for the first time introduces the fine particle plastic deformation as an irreversible energy sink. Then, the experiments of the cantilevered beam with the CID and that with the FPID are, respectively, carried out to investigate the behavior of FPID. The experimental results indicate that the FPID has a better performance in vibration damping than in the CID and the FPID works well in control of the vibration with frequency lower than 50 Hz, which is absent to the non-obstructive particle damper. Thus, the FPID has a bright and significant application future because most of the mechanical vibration falls in the range of low freqency.

Robust Landing Gear System Based on a Hybrid Momentum Exchange Impact Damper

2013 ◽  
Vol 36 (3) ◽  
pp. 776-789 ◽  
Author(s):  
Yohei Kushida ◽  
Susumu Hara ◽  
Masatsugu Otsuki ◽  
Yoji Yamada ◽  
Tatsuaki Hashimoto ◽  
...  
Keyword(s):  
Landing Gear ◽  
Gear System ◽  
Momentum Exchange ◽  
Impact Damper

Fundamental Study of Momentum-Exchange-Impact-Damper-Based Robust Landing Gear

2012 ◽  
Author(s):  
Yohei Kushida ◽  
Susumu Hara ◽  
Masatsugu Otsuki ◽  
Yoji Yamada ◽  
Tatsuaki Hashimoto ◽  
...  
Keyword(s):  
Landing Gear ◽  
Momentum Exchange ◽  
Fundamental Study ◽  
Impact Damper

scholarly journals A Rational Numerical Method for Simulation of Drop-Impact Dynamics of Oleo-Pneumatic Landing Gear

2021 ◽  
Vol 11 (9) ◽  
pp. 4136
Author(s):  
Rosario Pecora
Keyword(s):  
Numerical Method ◽  
Initial Conditions ◽  
Impact Load ◽  
Numerical Models ◽  
Landing Gear ◽  
Design Stage ◽  
Impact Dynamics ◽  
State Variables ◽  
Adopted Model ◽  
The Impact

Oleo-pneumatic landing gear is a complex mechanical system conceived to efficiently absorb and dissipate an aircraft’s kinetic energy at touchdown, thus reducing the impact load and acceleration transmitted to the airframe. Due to its significant influence on ground loads, this system is generally designed in parallel with the main structural components of the aircraft, such as the fuselage and wings. Robust numerical models for simulating landing gear impact dynamics are essential from the preliminary design stage in order to properly assess aircraft configuration and structural arrangements. Finite element (FE) analysis is a viable solution for supporting the design. However, regarding the oleo-pneumatic struts, FE-based simulation may become unpractical, since detailed models are required to obtain reliable results. Moreover, FE models could not be very versatile for accommodating the many design updates that usually occur at the beginning of the landing gear project or during the layout optimization process. In this work, a numerical method for simulating oleo-pneumatic landing gear drop dynamics is presented. To effectively support both the preliminary and advanced design of landing gear units, the proposed simulation approach rationally balances the level of sophistication of the adopted model with the need for accurate results. Although based on a formulation assuming only four state variables for the description of landing gear dynamics, the approach successfully accounts for all the relevant forces that arise during the drop and their influence on landing gear motion. A set of intercommunicating routines was implemented in MATLAB® environment to integrate the dynamic impact equations, starting from user-defined initial conditions and general parameters related to the geometric and structural configuration of the landing gear. The tool was then used to simulate a drop test of a reference landing gear, and the obtained results were successfully validated against available experimental data.

scholarly journals Release of the National Scheme’s Aboriginal and Torres Strait Islander Health and Cultural Safety Strategy 2020-2025; the impacts for podiatry in Australia: a commentary

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
James M. Gerrard ◽  
Shirley Godwin ◽  
Vivienne Chuter ◽  
Shannon E. Munteanu ◽  
Matthew West ◽  
...  
Keyword(s):  
Health Outcomes ◽  
First Nations ◽  
Torres Strait Islander ◽  
Collective Responsibility ◽  
Cultural Safety ◽  
Main Body ◽  
Torres Strait ◽  
The Impact ◽  
Torres Strait Islander Health ◽  
Safety Strategy

Abstract Background Developing since colonisation, Australia’s healthcare system has dismissed an ongoing and successful First Nations health paradigm in place for 60,000 years. From Captain James Cook documenting ‘very old’ First Nations Peoples being ‘far more happier than we Europeans’ and Governor Arthur Phillip naming Manly in admiration of the physical health of Gadigal men of the Eora Nation, to anthropologist Daisy Bates’ observation of First Nations Peoples living ‘into their eighties’ and having a higher life expectancy than Europeans; our healthcare system’s shameful cultural safety deficit has allowed for an Aboriginal and Torres Strait Islander child born in Australia today to expect to live 9 years less than a non-Indigenous child. Disproportionately negative healthcare outcomes including early onset diabetes-related foot disease and high rates of lower limb amputation in Aboriginal and Torres Strait Islander Peoples contribute to this gross inequity. Main body In 2020, the Australian Health Practitioner Regulation Authority released the National Scheme’s Aboriginal and Torres Strait Islander Health and Cultural Safety Strategy 2020–2025 - empowering all registered health practitioners within Australia to provide health care to Aboriginal and Torres Strait Islander Peoples that is inclusive, respectful and safe, as judged by the recipient of care. This recently released strategy is critically important to the podiatry profession in Australia. As clinicians, researchers and educators we have a collective responsibility to engage with this strategy of cultural safety. This commentary defines cultural safety for podiatry and outlines the components of the strategy in the context of our profession. Discussion considers the impact of the strategy on podiatry. It identifies mechanisms for podiatrists in all settings to facilitate safer practice, thereby advancing healthcare to produce more equitable outcomes. Conclusion Aboriginal and Torres Strait Islander Peoples access health services more frequently and have better health outcomes where provision of care is culturally safe. By engaging with the National Scheme’s Aboriginal and Torres Strait Islander Health and Cultural Safety Strategy, all registered podiatrists in Australia can contribute to achieving equity in health outcomes for Aboriginal and Torres Strait Islander Peoples.

scholarly journals Analysis on Force Transmission Characteristics of Two-Legged Shield Support under Impact Loading

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Qing-liang Zeng ◽  
Zhao-sheng Meng ◽  
Li-rong Wan ◽  
Cheng-long Wang
Keyword(s):  
Structural Design ◽  
Load Transfer ◽  
Impact Load ◽  
Force Transmission ◽  
Full Account ◽  
Flexible Bodies ◽  
Powered Support ◽  
Structural Design Optimization ◽  
Hinge Points ◽  
The Impact

To study the load transfer characteristics of a two-legged shield powered support, a numerical simulation model of the support was established using the multibody dynamics software ADAMS. The model took full account of the hydraulic-elastic deformation characteristics of the support, as a series spring-damper system was used to replace the leg and the equilibrium jack. The canopy, goaf shield, lemniscate bars, and equilibrium jack are equivalent to flexible bodies. The setting force of the leg was provided by the preload of the equivalent spring, the static roof load was simulated using a slope signal, and the impact load was simulated using a step signal. Using the model, the impact and excitation effects of each hinge joint of the support were analyzed under different impact load conditions across the canopy. The results show that the location of the impact load affects the force transmissions of all hinge points of the support. Both the impact effect and the excitation effect are at a minimum when the impact force is located near the leg action line. These results are useful for the adaptive control and structural design optimization of the support.

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